A field ion microscope study on vapor deposition of copper on tungsten

Abstract

Field ion microscopy observation was carried out on a copper thin film that was vapor deposited at a right angle to the tip axis onto one half of a tungsten tip cap. When copper was vapor deposited onto a tip kept at around 55 K, the deposit, which was made up of many fine crystallites and of a few larger crystallites at the interface with the substrate on each of the W{110} planes, was observed only on one half of the tip cap facing the evaporator. In addition, a well-ordered copper monolayer was observed on an area slightly wider than one half of the tip cap. By heating this deposit to 200, 300, or 400 K, recrystallization took place from the interface between the copper deposit and the substrate tungsten, and the thick copper area was reduced backwards to the direction of the evaporator. The recrystallization took place preferentially on some low index planes of tungsten. When copper was vapor deposited onto a tip kept at high temperatures (200, 300 or 400 K), copper crystals nucleated preferentially on W{110} planes and the condensed copper area spread to the shadow side by the forward migration of copper under the influence of impinging of depositing atoms.